Noticing some High Treble distortion with my HD558

My Sennheiser HD558 arrived a couple of days ago, and I'm loving it so far. Really good sound, not fatiguing at all, something that made me sell my previous Gamer Headphone ( I know, very stupid ) but I'm noticing some High Treble Distortion. It's connected to the Headphone Output of the X-Fi Titanium HD, no Headphone Amp.

The example I have to tell you when I hear it is Led Zeppelin III - Since I've Been Loving you - MP3 320kbps. I have checked the file on Reaper, it's not clipping, well below the clipping zone. The distortion happens around 6:15 - 6:20. I don't know if it's supposed to sound like that, maybe because of the recording equipments back then, and the HD558 is making me notice it much more than before.

My Sennheiser HD558 arrived a couple of days ago, and I'm loving it so far. Really good sound, not fatiguing at all, something that made me sell my previous Gamer Headphone ( I know, very stupid ) but I'm noticing some High Treble Distortion. It's connected to the Headphone Output of the X-Fi Titanium HD, no Headphone Amp.

The example I have to tell you when I hear it is Led Zeppelin III - Since I've Been Loving you - MP3 320kbps. I have checked the file on Reaper, it's not clipping, well below the clipping zone. The distortion happens around 6:15 - 6:20. I don't know if it's supposed to sound like that, maybe because of the recording equipments back then, and the HD558 is making me notice it much more than before.

The Titanium HD does not come with a true headphone amplifier and has a high impedance of 35-Ohms, which may or may not be causing the treble problem.

Tried using the E-MU Tracker Pre USB Interface, same thing. I Guess it's the music, I have not heard it with any other, actually I have with One from Creed, but looking that music with Reaper is ridiculous, so compressed with lots of clipping.

It's incredible how much better the Titanium HD DAC is to the E-MU Tracker Pre, which should be a pretty good one, much more clarity.

Tried using the E-MU Tracker Pre USB Interface, same thing. I Guess it's the music, I have not heard it with any other, actually I have with One from Creed, but looking that music with Reaper is ridiculous, so compressed with lots of clipping.

It's incredible how much better the Titanium HD DAC is to the E-MU Tracker Pre, which should be a pretty good one, much more clarity.